package main

func main() {
	println(modifyString("??yw?ipkj?"))
}
func modifyString(s string) string {
	str := []byte(s)
	n := len(s)
	for i := range str {
		if str[i] == '?' {
			for ch := byte('a'); ch <= 'c'; ch++ {
				if !(i > 0 && ch == str[i-1] || i < n-1 && ch == str[i+1]) {
					str[i] = ch
					break
				}
			}
		}
	}

	return string(str)
}
